IEEE 802.11 is a set of media access control (MAC) and physical layer (PHY) specification for implementing wireless local area network (WLAN) computer communication in Wi-Fi frequency bands (2.4, 3.6, 5, and 60 GHz). This standard provides the basis for wireless network products using the Wi-Fi frequency bands. For example, IEEE 802.11ac is a wireless networking standard in the 802.11 family, providing high-throughput WLANs on the 5 GHz band. Significant wider channel bandwidths (20 MHz, 40 MHz, 80 MHz, and 160 MHz) were proposed in the IEEE 802.11ac standard. The High Efficiency WLAN study group (HEW SG) is a study group within the IEEE 802.11 working group for considering the improvement of spectrum efficiency to enhance system throughput in high-density scenarios of wireless devices. TGax was formed in response to HEW SG, and tasked to work on the IEEE 802.11ax standard, which will become a successor to IEEE 802.11ac.
IEEE802.11ax seeks throughput enhancement in the dense deployed environment. Specifically, uplink (UL) and downlink (DL) user aggregation has been introduced to increase network efficiency. Transmission by UL Orthogonal Frequency Division Multiple Access (OFDMA) for non-access point (AP) stations can alleviate collision, and also enhance performance such as throughput rate and latency.